The disclosure relates to vapor compression systems. More particularly, the disclosure relates to economized reciprocating compressors.
Various economized reciprocating compressors have been proposed. In one example, there is staged compression with the main flow of refrigerant passing sequentially through two stages of cylinders and the economizer flow being introduced at the interstage. This multi-stage compression introduces additional valve flow losses and friction (because the refrigerant flow from the evaporator needs to pass through two set of valves and two set of pistons (in the first stage and second stage)). It also limits cooling capacity in that only one stage of two is drawing refrigerant into the compressor from the evaporator via the compressor suction port.
Another recent proposal involves isolating the banks of cylinders. Thus, the intake of one bank is at the compressor suction port whereas the intake of another bank is at the compressor economizer port and both discharge to the compressor discharge port. In a two-bank configuration, this would be associated with approximately 1:1 ratios of suction volumetric flow rate to economizer volumetric flow rate. In a three-bank situation wherein two banks draw from the suction port, this would have an approximate 2:1 ratio. Such low ratio of suction flow intake to the economizer port intake is undesirable because it results in low operating efficiency and reduced capacity.